Here is a run down of Morgan Stanley’s services:

“Corporations, organizations, and governments rely on Morgan Stanley as a global leader in investment banking. We advise clients on transactions including mergers, acquisitions, restructurings, initial public offerings (IPOs), convertibles, share repurchases, debt offerings, derivatives and more.“

Source:

https://www.morganstanley.com/what-we-do

Since it is not a company that derives its income from riba there is no prohibition in working for them.